US9724154B2 - Irrigated ablation catheter with multiple sensors - Google Patents

Abstract

Systems and methods are disclosed for providing and using an irrigated ablation catheter. The catheter may include a distal shell electrode having irrigation apertures. An insert disposed within the electrode has protrusions that mate with orifices in the shell of the electrode. Each protrusion has a port communicating with at least one interior lumen in the insert and a sensor is disposed in each port. A support seals the proximal end of the electrode and engages the insert. The plurality of sensors may be used to measure electrical and thermal characteristics surrounding the electrode and may help assess contact between the electrode and tissue and/or determine movement of the electrode during ablation.

Description

FIELD OF THE PRESENT DISCLOSURE

This disclosure relates generally to methods and devices for percutaneous medical treatment, and specifically to catheters, in particular, irrigated ablation catheters. More particularly, this disclosure relates to irrigated ablation catheters designs that support and stabilize micro-elements for accurate thermal and/or electrical sensing properties while providing reduced interference with irrigation of the ablation electrode.

BACKGROUND

Radiofrequency (RF) electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. Specifically, targeted ablation may be performed for a number of indications. For example, ablation of myocardial tissue is well known as a treatment for cardiac arrhythmias by using a catheter to apply RF energy and create a lesion to break arrhythmogenic current paths in the cardiac tissue. As another example, a renal ablation procedure may involve the insertion of a catheter having an electrode at its distal end into a renal artery in order to complete a circumferential lesion in the artery in order to denervate the artery for the treatment of hypertension.

In such procedures, a reference electrode is typically provided and may be attached to the skin of the patient or by means of a second catheter. RF current is applied to the tip electrode of the ablating catheter, and current flows through the media that surrounds it, i.e., blood and tissue, toward the reference electrode. The distribution of current depends on the amount of electrode surface in contact with the tissue as compared to blood, which has a higher conductivity than the tissue. Heating of the tissue occurs due to its electrical resistance. The tissue is heated sufficiently to cause cellular destruction in the target tissue resulting in formation of a lesion which is electrically non-conductive. The lesion may be formed in tissue contacting the electrode or in adjacent tissue. During this process, heating of the electrode also occurs as a result of conduction from the heated tissue to the electrode itself.

Correspondingly, irrigation of the ablation catheter may provide many benefits including cooling of the electrode and tissue to prevent overheating of tissue that can otherwise cause the formation of char and coagulum and even steam pops. Therefore, an irrigated ablation catheter may include one or more temperature sensors, such as thermocouples, thermistors or the like, to assess tissue temperature during an ablation procedure for avoiding such adverse occurrences. It is desirable that the sensed temperature accurately reflects the real temperature of the tissue and not merely tissue temperature which has been biased by the cooling irrigation fluid from the catheter. Moreover, an irrigated ablation catheter may alternatively or in addition include electrical sensors for multiple purposes, including measuring impedance to help determine lesion size, depth and transmurality, performing mapping functions or assessing tissue contact with the RF electrode.

Further, the distal end of an irrigated ablation catheter is subject to significant spatial and design constraints. Since the catheter gains access via an intravascular route, the overall diameter is limited and must be sufficiently flexible to navigate the tortuous anatomy. There must also be an irrigation conduit system to supply the cooling fluid. The distal end also needs to accommodate the above noted RF electrode, temperature sensors and electrical sensors, and the associated electrical connections as well as other functional components that may be included, such as contact force sensor systems, safety wires or other structures.

Accordingly, it would be desirable to provide an irrigated ablation catheter that has one or more temperature and/or electrical sensors positioned at the distal end. It is also desirable to reduce interference between such elements and the irrigation system. For example, it would be desirable to provide the sensors in a manner that increases the surface area of the RF electrode exposed to the irrigation fluid. Likewise, it would be desirable to provide the sensors in a manner that reduces the effect of the irrigation fluid on the measurements. As will be described in the following materials, this disclosure satisfies these and other needs.

SUMMARY

The present disclosure is directed to a catheter having an elongated body, an electrode mounted at a distal end of the elongated body, wherein the electrode is configured as a shell defining an interior space, a plurality of irrigation apertures formed in the shell and communicating with the interior space, an insert disposed within the interior space having a plurality of protrusions configured to mate with a corresponding plurality of orifices in the shell of the electrode, wherein each protrusion extends at least flush with an exterior surface of the electrode and has a port communicating with at least one interior lumen in the insert, a plurality of sensors, wherein each sensor is disposed within one of the ports of the protrusions and a support which forms a fluid tight seal with a proximal end of the electrode and engages a proximal end of the insert to stabilize the insert against rotational motion.

In one aspect, the insert may have at least one longitudinally extending arm with at least one protrusion. Further, the at least one arm may have an interior lumen in communication the port of the at least one protrusion. Still further, the at least one arm may have a plurality of protrusions, such that the interior lumen of the at least one arm is in communication with a plurality of ports. As desired, at least one guide tube may be provided to extend from a through-hole in the support to the interior lumen of the at least one arm.

In one aspect, each protrusion may have a shoulder positioned radially outwards from a surface of the arm, such that the shoulder engages an interior surface of the electrode surrounding the orifice. A minimum separation may be provided between the insert and an interior surface of the electrode, wherein the minimum separation is defined by a distance from the surface of the arm and the shoulder.

In one aspect, the insert may have a plurality of arms. Further, at least one passageway may be provided between the plurality of arms to allow circulation of irrigation fluid within the interior space.

In one aspect, the insert may be formed by an outer portion and an inner portion and wherein the outer portion and the inner portion mate to form the at least one interior lumen. The inner portion may support the outer portion against inward deflection.

In one aspect, at least some of the plurality of sensors may be temperature sensors. In another aspect, at least some of the plurality of sensors may be electrical sensors. Alternatively or in addition, at least one of the plurality of sensors may be a combined temperature and electrical sensor.

This disclosure is also directed to a method for the ablation of a portion of tissue of a patient by an operator. One suitable method includes inserting a catheter into the patient, wherein the catheter has an elongated body, an electrode mounted at a distal end of the elongated body, wherein the electrode is configured as a shell defining an interior space, a plurality of irrigation apertures formed in the shell and communicating with the interior space, an insert disposed within the interior space having a plurality of protrusions configured to mate with a corresponding plurality of orifices in the shell of the electrode, wherein each protrusion extends at least flush with an exterior surface of the electrode and has a port communicating with at least one interior lumen in the insert, a plurality of sensors, wherein each sensor is disposed within one of the ports of the protrusions and a support which forms a fluid tight seal with a proximal end of the electrode and engages a proximal end of the insert to stabilize the insert against rotational motion, then connecting the catheter to a system controller capable of receiving signals from the plurality of sensors and delivering power to the electrode and subsequently controlling the power to the electrode to ablate tissue.

In one aspect, power to the electrode to ablate tissue may be controlled based at least in part on measurements from the plurality of sensors.

In one aspect, irrigation fluid may be delivered to the interior space based at least in part on measurements from the plurality of sensors.

In one aspect, contact of the electrode with tissue may be distinguished from contact of the electrode with blood based at least in part on measurements from the plurality of sensors.

In one aspect, a degree of contact of the electrode with tissue may be estimated based at least in part on measurements from the plurality of sensors.

In one aspect, movement of the electrode during ablation may be determined based at least in part on measurements from the plurality of sensors.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages will become apparent from the following and more particular description of the preferred embodiments of the disclosure, as illustrated in the accompanying drawings, and in which like referenced characters generally refer to the same parts or elements throughout the views, and in which:

FIG. 1 is a perspective view of a catheter in accordance with an embodiment of the present invention.

FIG. 2 is a perspective view of an electrode at the distal end of the catheter ofFIG. 1 in accordance with an embodiment of the present invention.

FIG. 3 is an isometric view of an insert accommodating a plurality of sensors within the electrode in accordance with an embodiment of the present invention.

FIG. 4 is a cross-sectional view of the distal end of the catheter, taken at line A-A ofFIG. 2, in accordance with an embodiment of the present invention.

FIG. 5 is a cross-sectional view of the distal end of the catheter, taken at line B-B ofFIG. 4, in accordance with an embodiment of the present invention.

FIG. 6 is an isometric view of another insert accommodating a plurality of sensors within the electrode in accordance with an embodiment of the present invention.

FIG. 7 is a cross-sectional view of the distal end of the catheter, taken at line C-C ofFIG. 6, in accordance with an embodiment of the present invention.

FIG. 8 is a schematic view of an ablation system in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

At the outset, it is to be understood that this disclosure is not limited to particularly exemplified materials, architectures, routines, methods or structures as such may vary. Thus, although a number of such options, similar or equivalent to those described herein, can be used in the practice or embodiments of this disclosure, the preferred materials and methods are described herein.

It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments of this disclosure only and is not intended to be limiting.

The detailed description set forth below in connection with the appended drawings is intended as a description of exemplary embodiments of the present disclosure and is not intended to represent the only exemplary embodiments in which the present disclosure can be practiced. The term “exemplary” used throughout this description means “serving as an example, instance, or illustration,” and should not necessarily be construed as preferred or advantageous over other exemplary embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the exemplary embodiments of the specification. It will be apparent to those skilled in the art that the exemplary embodiments of the specification may be practiced without these specific details. In some instances, well known structures and devices are shown in block diagram form in order to avoid obscuring the novelty of the exemplary embodiments presented herein.

For purposes of convenience and clarity only, directional terms, such as top, bottom, left, right, up, down, over, above, below, beneath, rear, back, and front, may be used with respect to the accompanying drawings. These and similar directional terms should not be construed to limit the scope of the disclosure in any manner.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one having ordinary skill in the art to which the disclosure pertains.

Finally, as used in this specification and the appended claims, the singular forms “a, “an” and “the” include plural referents unless the content clearly dictates otherwise.

As illustrated inFIG. 1, the present disclosure includes irrigatedablation catheter10 with a distal tip section that includeselectrode12 adapted for contact with target tissue.Catheter10 according to the disclosed embodiments comprises an elongated body that includes an insertion shaft orcatheter body14 having a longitudinal axis, and anintermediate section16 distal of the catheter body that optionally may be uni- or bi-directionally deflectable off-axis from the catheter body as indicated. Proximal ofcatheter body14 iscontrol handle18 that allows an operator to maneuver the catheter, including by deflectingintermediate section14 when a steerable embodiment is employed. For example, control handle18 may includedeflection knob20 that is pivoted in a clockwise or counterclockwise direction for deflection in the respective direction. In other embodiments, other steerable designs may be employed, such as the control handles for manipulating multiple control wires as described, for example, in U.S. Pat. Nos. 6,468,260, 6,500,167, and 6,522,933 and U.S. patent application Ser. No. 12/960,286, filed Dec. 3, 2010, the entire disclosures of which are incorporated herein by reference.

Catheter body14 is flexible, i.e., bendable, but substantially non-compressible along its length and may be of any suitable construction and made of any suitable material. In one aspect, an outer wall made of polyurethane or PEBAX may have an imbedded braided mesh of stainless steel or the like, as is generally known in the art, to increase torsional stiffness ofcatheter body14 so that, when the control handle20 is rotated, theintermediate section16 will rotate in a corresponding manner. Depending upon the intended use, the outer diameter ofcatheter body14 may be approximately 8 french, and in some embodiments, may be 7 french. Likewise the thickness of the outer wall ofcatheter body14 may be thin enough so that a central lumen may accommodate any desired wires, cables and/or tubes, as will be described in further detail below. The useful length of the catheter, i.e., that portion that can be inserted into the body may vary as desired. In exemplary embodiments, the useful length may range from about 110 cm to about 120 cm. The length of theintermediate section16 may correspond to a relatively small portion of the useful length, such as from about 3.5 cm to about 10 cm, and in some embodiments, from about 5 cm to about 6.5 cm.

Details regarding one embodiment of the distal tip ofcatheter10 are illustrated inFIGS. 2-5. Referring now toFIG. 2,electrode12 is configured as an elongated, generallycylindrical portion22 and an atraumatic dome-shapedportion24 at the distal end. The shell ofelectrode12 defines an interior cavity that is in fluid communication with a lumen extending the length ofcatheter body14 to supply irrigation fluid. A plurality ofirrigation apertures26 are distributed substantially evenly across the surface ofelectrode12, through which fluid entering and filling the cavity may exit to outside of theelectrode12, to provide cooling ofelectrode12 and the environmentadjacent electrode12 as desired. The shell ofelectrode12 may be made of any suitable electrically-conductive material, such as palladium, platinum, gold, iridium and combinations and alloys thereof, including, Pd/Pt (e.g., 80% Palladium/20% Platinum) and Pt/Ir (e.g., 90% Platinum/10% Iridium).

Disposed withinelectrode12 isinsert28, schematically shown in phantom, and configured to position a plurality of sensors at desired locations with respect toelectrode12.Insert28 hasmultiple protrusions30 that align withsensor orifices32 formed inelectrode12. Eachprotrusion30 has aport34 configured to receive a sensor (not shown in this view).Insert28 may be formed from any suitable material having appropriate electrical and thermal insulating properties, such as PEEK. The number ofprotrusions30 may correspond to the number of sensors being employed. In this embodiment, three proximal protrusions are radially spaced by approximately 120 degrees aboutcylindrical portion22 and three distal protrusions are radially spaced by approximately 120 degrees about dome-shapedportion24. This allowsinsert28 to have a substantially triangular configuration, such thatprotrusions30 are positioned at the apexes of the insert. In other embodiments, other suitable configurations may be employed.Protrusions30 may be sized to either extend beyond or to be flush with the shell ofelectrode12 as desired. For example,protrusions30 extend from the shell a distance ranging from 0.05-0.3 mm and in one embodiment may extend between about 0.07 and 0.13 mm.

In one aspect, insert28 may be configured to exhibit reduced contact withelectrode12. For example, in the embodiment shown, insert28 contacts electrode12 only throughprotrusions30. Accordingly, aminimum separation36 may be maintained between the body ofinsert28 and the inner surface ofelectrode12. As will be appreciated, this facilitates circulation and even distribution of irrigation fluid, that may be supplied through lumen38 (shown in phantom), as well as reducing interference with the exit of the irrigation fluid throughapertures26. Additionally, passageways40 formed ininsert28 may also facilitate irrigation.

Additionaldetails regarding insert28 are depicted inFIG. 3. In this view,electrode12 has been removed to help show aspects ofinsert28. As can be seen,protrusions30 includeannular shoulders42 configured to engage the inner surface ofelectrode12.Shoulders42 may have a surface that is complimentary to thecylindrical portion22 or dome-shapedportion24 ofelectrode12 as appropriate. The width ofshoulders42 may be defined by the difference between the diameter of abase portion44 and the diameter ofinner portion46. The diameter ofinner portion46 is sized to mate with sensor orifices32 (shown inFIG. 2) inelectrode12. Further, the depth ofinner portion12, together with the thickness of the shell ofelectrode12 results inprotrusions30 that either extend outward from or are flush with the outer surface ofelectrode12. Similarly,annular shoulder42 extends radially outward from the surface ofinsert28, such that the depth ofbase portion44 establishes theminimum separation36 shown inFIG. 2 between the inner surface ofelectrode12 andsurface48 on the body ofinsert28.

In this embodiment, insert28 includes three longitudinally extendingarms50, each having a hollow interior portion that communicates withports34 to allow routing of leads and wires tosensors52.Arms50 are connected atdistal crown portion54.Passageways40 as described above may be formed betweenarms50 as well as by a central opening incrown portion54. Depending on the intended use and the number of sensors being provided, the configuration ofinsert28 may be adapted as desired, such as by featuring two or four arms, for example. In one aspect, eacharm50 may include at least twoprotrusions30 to accommodate at least two sensors, such as one proximal and one distal.

Sensors52 may be any combination of temperature sensors, e.g., thermistor, thermocouple, fluoroptic probe, and the like, or electrical sensors, e.g., micro-electrodes. Any temperature sensor junctions located at or near the end ofprotrusions30 and may be potted with a thermally conductive adhesive. Any wires or leads associated withsensors52 may be routed througharms50 andports34 as appropriate. As will be appreciated, this configuration isolatessensors52 fromelectrode12 and the irrigation fluid. In one aspect, insert28 serves to thermally insulatesensors52. Accordingly, a more accurate measurement of tissue and environmental temperature may be obtained by reducing biasing fromelectrode12 or the circulating irrigation fluid. In another aspect, insert28 also serves to electrically insulatesensors52 to allow more accurate measurement. Similarly, any wires and/or leads are also thermally and electrically insulated, as well as being sealed against corrosion from the irrigation fluid. In one aspect, eachsensor52 positioned by arespective protrusion30 may be configured to sense a plurality of measurements. For example, one ormore sensors52 may function both as a micro-thermistor and a micro-electrode. According to one embodiment, thermistor wires as well as an electrode lead wire may be connected to a shell cap electrode ofsensor52. Each wire may be isolated from each other by any suitable technique, such as by employing a suitable electrically nonconductive and non-thermally insulative material to fill the interior ofarm50 after placement ofsensor52.

Insert28 is stabilized withinelectrode12 bysupport54, which includes a disc-shapedbase56 and adistally projecting key58.Base56 may have a diameter corresponding to the inner diameter ofelectrode12 and may be secured in any suitable manner, such as by welding60.Key58 is configured to fit withinrecess62 ofinsert28, formed by the proximal portions ofarms50, to stabilizeinsert28 against axial rotation and possible displacement ofsensors52.Support54 may provide a fluid tight seal withelectrode12 while routing leads and wires associated withelectrode12 andsensors52 and irrigation fluid from lumens extending throughcatheter body14. For example,central conduit64 may be in communication with lumen38 (shown inFIG. 2), to conduct irrigation fluid topassageways40, for circulation within the interior ofelectrode12 and eventual exit throughapertures26. As shown inFIG. 5 below, through-holes insupport54 may align with the interior ofarms50 to accommodate passage of wires tosensors52.Support54 may also include one or more radial conduits66 (one shown inFIG. 3) to accommodate leads for energizingelectrode12, leads for position sensors, a safety wire to prevent loss of the distal end ofcatheter10, or other suitable purposes.Support54 may be formed of any suitable electrically- and thermally-conductive material, such as palladium, platinum, gold, iridium and combinations and alloys thereof, including, Pd/Pt (e.g., 80% Palladium/20% Platinum) and Pt/Ir (e.g., 90% Platinum/10% Iridium).

Turning now toFIG. 4, an axial cross sectional view taken along line A-A indicated inFIG. 2 is shown. The inner surface ofelectrode12 definesirrigation reservoir68, which may be supplied with irrigation fluid throughconduit64.Proximal portions70 ofarms50 are positioned apart from the interior surface ofelectrode12 byminimum separation36, defined by the depth ofbase portion44 ofprotrusions30 as described above. In this embodiment,proximal portions70 do not have the hollow interior, which is formed distally. Rather,proximal portions70 receiveguide tubes72 and direct them towards the interiors ofarms50 as shown below in the context ofFIG. 5.Guide tubes72 generally extend from through-holes insupport54 to the interiors ofarms50 to seal, insulate and/or protectwires74 which connectsensors52.Guide tubes72 may be formed of any suitable material that is fluid-tight, electrically-nonconductive, thermally-insulating, and sufficiently flexible, e.g., polyimide, to form a thin-walled tubing.FIG. 4 also illustrates the cooperation between recess62 (schematically represented by dashed lines) andkey58 ofsupport54 to stabilize against axial rotation.Key58 also may engageproximal portions70 to prevent or reduce deflection inwards ofarms50.

As noted above,support54 may include one or moreradial conduits66 as desired. In this embodiment, oneconduit66 receivesRF coil76 used to energizeelectrode12.Other conduits66 may be used for any suitable purpose, including routing and/or anchoringsafety wire78 to facilitate retrieval of the electrode assembly or other distal portions ofcatheter10 should they become detached during a procedure.Safety wire78 may be formed from Vectran™ or other suitable materials. In other embodiments, one or more ofradial conduits66 may accommodate electromagnetic position sensors that may be used in conjunction with a mapping system to aid visualization of the placement of the distal end ofcatheter10 within a patient's anatomy and/or a force or contact sensing system. Details regarding such aspects may be found in U.S. patent application Ser. Nos. 11/868,733 and 13/424,783, both of which are incorporated herein by reference in their entirety.

Further details of one embodiment of the distal tip ofcatheter10 are shown inFIG. 5, which is a longitudinal cross-sectional view taken at line B-B indicated inFIG. 4. As described above,electrode12 may be secured to disc-shapedportion56 ofsupport54.Insert28 is positioned within the interior ofelectrode12, withprotrusions30 mating withsensor orifices32.Inner portion46 ofprotrusion30 extends throughorifice32, whileshoulder42 engages the inner surface ofelectrode12. As described above, the surfaces ofarms50 may be recessed as defined by the depth ofbase portion44 to maintain spacing betweeninsert28 andelectrode12, thereby improving exposure to irrigation fluid.Guide tube72 extends betweeninterior lumen80 ofarm50 and through-hole82 ofsupport54 to routewires74 from sensor52 (onlydistal sensor52 is shown for clarity, with the sensor removed from proximal port34). Wires and leads84 may similarly be routed throughradial conduit66 to coupleRF coil76. In this embodiment,safety wire78 may extend through and be anchored to support54. Alternatively,safety wire78 may be anchored in a suitable manner to insert28.

A different embodiment according to the techniques of this disclosure is schematically depicted inFIG. 6. In a similar manner toFIG. 3,electrode12 has been removed to showdetails regarding insert90 andsupport92.Insert90 may be formed fromouter portion94 andinner portion96. In a similar manner to the other disclosed embodiments,outer portion94 has a plurality ofprotrusions30, each having aport34 to accommodate a sensor (not shown in this view, but may incorporate any of the features described above).Outer portion94 may include longitudinally extendingarms98, each having one ormore protrusions30, andinner portion96 may have corresponding longitudinally extendingarms100. Afterouter portion94 is positioned withinelectrode12,inner portion96 may be fit to prevent inward deflection ofarms98. In one aspect,outer arms98 may be somewhat flexible to facilitate manufacture, so that the arms may be biased inwards when positioned withinelectrode12 and then allowed to return to a native configuration whenprotrusions30 are properly aligned withsensor orifices32 inelectrode12, as described above. As shown, this embodiment includes three radial protrusions and three distal protrusions, respectively spaced radially at about 120 degrees with respect to each other. Eachprotrusion30 on onearm98 may communicate with an interior lumen102 (one shown in phantom), formed wheninner portion96 is mated withouter portion94.

Support92 may include disc-shapedportion104 to be secured toelectrode12 and key106 to stabilizeinsert90 against rotation.Guide tubes108 may extend throughsupport92 to the respectiveinterior lumens102.Central conduit110 may deliver irrigation fluid to the interior space defined byelectrode12. In this embodiment, the surfaces ofarms98 are configured to rest against the interior surface ofelectrode12. Accordingly, contact betweeninsert90 is confined to longitudinal regionsadjacent protrusions30, leaving substantial portions of the interior surface ofelectrode12 exposed to irrigation fluid. In other embodiments,protrusions30 may include shoulders as described above to increase exposure of the interior surface ofelectrode12. Further, spacing between each pair ofarms98 and100 facilitates circulation of irrigation fluid within the interior ofelectrode12. As in the other embodiments of this disclosure, insert90 may be formed from a suitable electrically- and thermally-insulative material, to help increase the accuracy of sensors disposed withinports34.Support92 andelectrode12 to be used in this embodiment may be formed from a suitable electrically- and thermally-conductive material, such as palladium, platinum, gold, iridium and combinations and alloys thereof as described above.

An axial cross-sectional view of the embodiment shown inFIG. 6, taken along line C-C, is depicted asFIG. 7. At least a portion ofinterior lumen102 may be formed by complimentary surfaces ofouter arm98 andinner arm100 as shown. As discussed above, portions ofkey106 fit between the proximal ends of arm pairs98 and100 to stabilizeinsert90 against rotational motion.

According to the techniques of this disclosure,protrusions30 may be used to providecatheter10 withmultiple sensors52. In one aspect, each sensor may measure temperature and electrical characteristics as described above, to allow for direct monitoring of micro ECG signals and/or micro impedance values using eachsensor52. As will be appreciated, use of either, or both, ECG and impedance provide the ability to determine the contacting tissue at the location of each sensor and help distinguish between blood and tissue. This information may be utilized to confirm sufficient tissue coupling prior to delivery of RF ablation. This may be employed alternatively or in addition to the use of contact force sensors. Additionally, monitoring of electrical feedback from a plurality ofsensors52 distributed acrosselectrode12 may allow for estimation of a degree of contact betweenelectrode12 and tissue. For example, the measurements may be used to estimate the percentage of the surface ofelectrode12 that is coupled with tissue. In turn, this may be used to better characterize the efficacy of RF delivery by determining what portion of the energy is delivered to tissue as compared to the surrounding blood.

In another aspect, the array ofsensors52 according to the techniques of this disclosure may provide improved temperature response to facilitate determination of catheter movement. As will be appreciated, draggingcatheter10 along tissue may result in frequent rise and fall of temperature response fromtissue contacting sensors52. For example, ablations at a first position followed by movement to a new location may correspond to temperature increase during RF delivery followed by an abrupt decrease in interface temperature at the time of movement, and then by a temperature increase when RF delivery occurs at the new location. Consequently, the ability to quickly detect catheter movement using sensed temperature in this manner may allow for lesion assessment algorithms to “reset” mid ablation and account for detected movement.

In comparison to conventional RF ablation catheters, the techniques of this disclosure represent notable benefits. Prior to ablation, tissue and blood are at a similar temperature preventing use of temperature sensors from being utilized to determine contact, or more specifically areas of an electrode in contact. Contact force catheters are capable of demonstrating contact with tissue but do not provide an indication as to how much of the electrode is in contact with tissue. Further, such conventional contact force technologies may provide information regarding the contact with tissue. However, they do not provide an indication of movement during RF delivery by using the temperature sensing described above. The use ofprotrusions30 to accommodatemultiple sensors52 provides sufficient resolution and response time to indicate ablation site movement.

Use ofcatheter10 in an ablation procedure may follow techniques known to those of skill in the art.FIG. 8 is a schematic, pictorial illustration of asystem200 for renal and/or cardiac catheterization and ablation, in accordance with an embodiment of the present invention.System200 may be based, for example, on the CARTO™ mapping systems, produced by Biosense Webster Inc. (Diamond Bar, Calif.) and/or SmartAblate or nMarq RF generators. This system comprises an invasive probe in the form ofcatheter10 and a control and/orablation console202. Anoperator204, such as a cardiologist, electrophysiologist or interventional radiologist, insertsablation catheter10 into and through the body of apatient206, such as through a femoral or radial access approach, so that a distal end ofcatheter10, in particular,electrode12, engages tissue at a desired location or locations, such as a chamber ofheart208 ofpatient206.Catheter10 is typically connected by a suitable connector at its proximal end to console202.Console202 comprises aRF generator208, which supplies high-frequency electrical energy via the catheter for ablatingtissue210 at the locations engaged byelectrode12.

Console202 may also use magnetic position sensing to determine position coordinates of the distal end ofcatheter10 inside the body of thepatient206. For this purpose, a driver circuit inconsole202 drives field generators to generate magnetic fields within the body ofpatient206. Typically, the field generators comprise coils, which are placed below the patient's torso at known positions external to the patient. These coils generate magnetic fields in a predefined working volume that contains the area of interest. A magnetic field sensor within distal end ofcatheter10, such asposition sensor78, generates electrical signals in response to these magnetic fields. A signal processor inconsole202 may process these signals in order to determine the position coordinates of the distal end, typically including both location and orientation coordinates. This method of position sensing is implemented in the above-mentioned CARTO system and is described in detail in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, in PCT Patent Publication WO 96/05768, and in U.S. Patent Application Publications 2002/0065455 A1, 2003/0120150 A1 and 2004/0068178 A1, whose disclosures are all incorporated herein by reference.

Console202 may includesystem controller212, comprising aprocessing unit216 communicating with amemory214, wherein is stored software for operation ofsystem200.Controller212 may be an industry standard personal computer comprising a general purpose computer processing unit. However, in some embodiments, at least some of the functions of the controller are performed using custom designed application specific integrated circuits (ASICs) or a field programmable gate array (FPGA).Controller212 is typically operated by theoperator204 using suitable input peripherals and a graphic user interface (GUI)218 which enable the operator to set parameters of thesystem200.GUI218 typically also displays results of the procedure to the operator. The software inmemory214 may be downloaded to the controller in electronic form, over a network, for example. Alternatively or additionally, the software may be provided on non-transitory tangible media such as optical, magnetic or electronic storage media. In some embodiments, one or more position sensors may send signals to console202 to provide an indication of the pressure onelectrode12. Signals fromwires74 may be provided tosystem controller212 to obtain measurements fromsensors52. Such signals may be used to provide impedance and/or ECG readings at the location corresponding tosensor52. Similarly, such signals may be used to provide a temperature reading at the location ofsensor52.

Typically, during an ablation, heat is generated by the RF energy in the tissue of the patient to effect the ablation and some of this heat is reflected to theelectrode12 causing coagulation at and around the electrode.System200 irrigates this region throughirrigation apertures26 and the rate of flow of irrigation is controlled byirrigation module220 and the power (RF energy) sent to electrode12 is controlled byablation module222. As noted above,system controller212 may use electrical and thermal characteristics measured by the plurality ofsensors52 to characterize aspects of the ablation process. For example, measurements fromsensors52 may be used to determine the contacting tissue at the location of each sensor and help distinguish between blood and tissue. Further, the percentage of the surface ofelectrode12 that is coupled with tissue may be estimated. As another example, measurements fromsensors52 may help determine movement ofelectrode12 during an ablation. Still further, information fromsensors52 may be used to determine the lesion size and depth. Details regarding this aspect may be found in U.S. patent application Ser. No. 13/113,159, entitled “Monitoring Tissue Temperature Using an Irrigated Catheter” the teachings of which is hereby incorporated by reference in its entirety. As yet another example,sensors52 may also provide intracardiac electrocardiograms tosystem controller212, to be used for determining when the tissue site being ablated is no longer conducting arrhythmogenic currents.

Described herein are certain exemplary embodiments. However, one skilled in the art that pertains to the present embodiments will understand that the principles of this disclosure can be extended easily with appropriate modifications to other applications.

Claims (20)

What is claimed is:

1. A catheter, comprising:

an elongated body;

an electrode mounted at a distal end of the elongated body, wherein the electrode is configured as a shell defining an interior space;

a plurality of irrigation apertures formed in the shell and communicating with the interior space;

an insert disposed within the interior space having a plurality of protrusions configured to mate with a corresponding plurality of orifices in the shell of the electrode, wherein each protrusion extends at least flush with an exterior surface of the electrode and has a port communicating with at least one interior lumen in the insert;

a plurality of sensors, wherein each sensor is disposed within one of the ports of the protrusions; and

a support which forms a flight tight seal with a proximal-most end of the electrode and engages a proximal end of the insert to stabilize the insert against rotational motion.

2. The catheter ofclaim 1, wherein the insert comprises at least one longitudinally extending arm with at least one protrusion.

3. The catheter ofclaim 2, wherein the at least one arm has an interior lumen in communication the port of the at least one protrusion.

4. The catheter ofclaim 3, wherein the at least one arm has a plurality of protrusions, such that the interior lumen of the at least one arm is in communication with a plurality of ports.

5. The catheter ofclaim 3, further comprising at least one guide tube extending from a through-hole in the support to the interior lumen of the at least one arm.

6. The catheter ofclaim 2, wherein each protrusion has a shoulder positioned radially outwards from a surface of the arm, such that the shoulder engages an interior surface of the electrode surrounding the orifice.

7. The catheter ofclaim 6, further comprising a minimum separation between the insert and an interior surface of the electrode, wherein the minimum separation is defined by a distance from the surface of the arm and the shoulder.

8. The catheter ofclaim 2, further comprising a plurality of arms.

9. The catheter ofclaim 8, further comprising at least one passageway between the plurality of arms to allow circulation of irrigation fluid within the interior space.

10. The catheter ofclaim 3, wherein the insert comprises an outer portion and an inner portion and wherein the outer portion and the inner portion mate to form the at least one interior lumen.

11. The catheter ofclaim 10, wherein the inner portion supports the outer portion against inward deflection.

12. The catheter ofclaim 1, wherein at least some of the plurality of sensors are temperature sensors.

13. The catheter ofclaim 1, wherein at least some of the plurality of sensors are electrical sensors.

14. The catheter ofclaim 1, wherein at least one of the plurality of sensors is a combined temperature and electrical sensor.

15. A method for the ablation of a portion of tissue of a patient by an operator comprising:

inserting a catheter into the patient, wherein the catheter comprises:

an elongated body;

an electrode mounted at a distal end of the elongated body, wherein the electrode is configured as a shell defining an interior space;

a plurality of irrigation apertures formed in the shell and communicating with the interior space;

an insert disposed within the interior space having a plurality of protrusions configured to mate with a corresponding plurality of orifices in the shell of the electrode, wherein each protrusion extends at least flush with an exterior surface of the electrode and has a port communicating with at least one interior lumen in the insert;

a plurality of sensors, wherein each sensor is disposed within one of the ports of the protrusions; and

a support which forms a flight tight seal with a proximal-most end of the electrode and engages a proximal end of the insert to stabilize the insert against rotational motion;

connecting the catheter to a system controller capable of receiving signals from the plurality of sensors and delivering power to the electrode; and

controlling the power to the electrode to ablate tissue.

16. The method ofclaim 15, wherein controlling the power to the electrode to ablate tissue is based at least in part on measurements from the plurality of sensors.

17. The method ofclaim 15, further comprising delivering irrigation fluid to the interior space based at least in part on measurements from the plurality of sensors.

18. The method ofclaim 15, further comprising distinguishing contact of the electrode with tissue from contact of the electrode with blood based at least in part on measurements from the plurality of sensors.

19. The method ofclaim 15, further comprising estimating a degree of contact of the electrode with tissue based at least in part on measurements from the plurality of sensors.

20. The method ofclaim 15, further comprising determining movement of the electrode during ablation based at least in part on measurements from the plurality of sensors.

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